Cook Extension Ag Update 8/5/26 | UGA Extension Cook County

Cotton – Silverleaf Whiteflies and Jassid Update

Below is information taken from an article by Phillip Roberts and Alana Jacobson.

Silverleaf Whiteflies – The goal is to initiate control measures just prior to the period of most rapid SLWF population development (i.e. reproduction in the field). It is critically important that initial insecticide applications are well timed. If you are late with the initial application control will be very difficult and expensive in the long run. It is nearly impossible to regain control once the population reaches outbreak levels.

SLWF Threshold: Treat when 50 percent of sampled leaves (sample 5th expanded leaf below the terminal) are infested with multiple immatures (=5 per leaf).
Insect Growth Regulators (Knack and Courier): use of IGRs are the backbone of SLWF management programs in cotton. Effects on SLWF populations are generally slow due to the life stages targeted by IGRs, however these products have long residual activity and perform very well when applied on a timely basis.
Use of other insecticide options (non-IGRs) which have quicker effects on SLWF infestations would be preferred if you are late with the initial spray. These quick knockdown sprays will allow you to “catch up” and can be followed by an IGR.

Cotton Jassid – To date we have detected jassids in 16 counties in 2026. This time a year ago (August 7, 2025) we had detected jassids in 33 counties. There is no question that the cold temperatures significantly reduced jassids across Georgia.

Closeup of cotton jassid. — Jassid and shed jassid skin on right (image from Jeremy Kichler). Adult jassids will have two black dots near ends of their wings. Potato leafhoppers (not 3-cornered alfalfa hoppers) found in peanuts look similar but will not have the two black dots.

cotton plant affected by cotton jassid. — Jassid hopper burn. Plants that show these symptoms are usually first noticed on edges of cotton fields.

Scouting for Jassids – When scouting for jassids examine the 4th expanded main stem leaf below the terminal. Sample this leaf on a minimum of 25 plants per field (sampling more leaves is better). If jassids reach a mean of 1 jassid per leaf treatment is recommended. Once the threshold is triggered it will be important to make a timely application. If a grower struggles to be timely with an application, you may need to be more aggressive if populations are building. The chart below is a general guide of expected efficacy of insecticides we tested in the southeast during 2025. Some insecticides were tested more than others (i.e. Carbine has 9 data points, Venom only has 2 data points) so we cannot make direct comparisons. But this chart does have some value. I interpret this chart that insecticides highlighted in green would be used if jassids triggered threshold. Products in orange provide suppression but may be of value if a grower cannot come back and make a timely application based on scouting. It is also important to note that bifenthrin will not provide control of jassids.

Lesser cornstalk borer in peanut stem. — Lesser Cornstalk Borer in peanut stem – despite rains.

Closeup of white mold in peanut. — Peanut White Mold Sclerotia (brown/tan BB structures that grow on the white fuzz). When sclerotia first develop they will be tan or white then get a darker brown as they age. Peanut white mold is getting more prevalent and conditions are perfect for its development. This may not be a year to skimp on peanut fungicides.

Tucker Price 229-507-8862.